For safe operation of an infrastructure that can have a grave influence on the society in the event of an accident, precise monitoring of the status of industrial machines is highly important. For example, a conventional anomaly detection system for a transport vehicle detects occurrence of an abnormality by obtaining various measurements with sensors during running.
However, the conventional anomaly detection system does not directly measure a measurement target such as a transformer, a resistor, a wheel, an electric motor and a gear but indirectly obtains measurements of the measurement target through calculation from measurements of surroundings of the measurement target. Consequently, the conventional anomaly detection system is easily affected by an environmental factor such as the running pattern and the meteorological condition and can hardly grasp the accurate measurement variation by excluding the influence of the environment.
Japanese Patent JP2010-179706A describes an anomaly detection system that judges whether a variation of a measurement value is abnormal or not by calculating a representative value of surface measurement values of a measurement target under the same condition and comparing the measurement value with the representative value under the same condition. The anomaly detection system disclosed in Japanese Patent JP2010-179706A can detect occurrence of an abnormality based only on the measurement value variation caused by the occurrence of the abnormality by excluding the influence of the ambient environment by designating, as a representative value, a value determined based on a measurement value variation that normally occurs and subtracting the representative value from each measurement value under the same condition.
However, variation that is detected is not limited to change in temperature. In order to detect occurrence of an abnormality, it is especially important to stably detect the variation even when an external environment is fluctuating.
The present invention has been made in view of the above situation, and the object is to provide a method, apparatus and computer program for detecting occurrence of an abnormality that make it possible to more objectively judge whether fluctuation of the physical quantity of a detection target is abnormal or not even when an external environment is fluctuating.